Rotatory electric tube-furnace.



No. 756,891. PATENTBD APR. 12, 1904.

H. N. POTTER. l

ROTATORY ELECTRIC TUBE JFURNACE.

APPLICATION FILED 11011.21, 1901.

No MODEL.

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UNiTED STATESn resented April 12, 1904.

PATENT OFFICE.

HENRY NOEL POTTER, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO GEO.WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

ROTATORY ELECTRIC TuBE-FURNACE.

SPECIFICATION forming part of Letters Patent No. 756,891, dated April12, 1904.

Application filed November 21, 1901. Serial No. 83,078. (No model.)

To a/ZZ whom, it may concern:

Be it known that I, HENRY NOEL POTTER, a citizen of the United States,and a resident of New Rochelle, in the county of Westchester and Stateof New York, have invented cer tain new and useful Improvements inRotatory Electric Tube-Furnaces, of whichthe following is aspecification. Y Owing to the fact that magnesia is the only knownmetallic oXid which is not reduced by carbon at high temperatures,forming a carbid therewith, it has been proposed by Moissan and othersto construct furnaces the main body of which is of carbon and the liningof magnesia. Moissan built such furnaces, heated by the electric arcinside the furnaces. Through the furnaces he passed a carbon tube,within which he carried out reactions not readily possible in contactwith the arc-vapors. An objection to this arrangement is that it leadsnecessarily to an unequal distribution of the heat in the interior ofthe tube. Besides, the arc-furnace cannot be as thoroughly jacketed asthe tube itself, for which reason more heat is required than if the tubewere heated by passing electric current di; rectly through it. It has,indeed, been suggested that a carbon tube constituting the main part ofa furnace-wall shall be heated by the passage of current, an independenttube of zirconia, magnesia, or the like being inserted within the carbontube and designed to act as the lining of the furnace. 4It is found,however', that such a lining-tube When made of magnesia and subjected tothe great heat developed in the tube of carbon undergoes great shrinkageand buckles out of shape, so that the lining is of small practicalutility. When zirconia is used, carbid of zirconium is formed, and witheither of the materials named disturbances of the reactions withinv thefurnace and of the tube itself are liable to take place by reason of theporosity of the lining material. ismelted, it becomes very dense,solidifying on cooling into a transparent non-porous crystallinemass,through Which vapors cannot pass. Being under these conditions in thestate of highest density and having no fur- When, however, magnesia`ther tendency to polymerize, the magnesia does not shrink under theaction of heat. The

present invention contemplates utilizing these.

properties of fused magnesia in the construction of an electric furnacein which a carbon tube is lined with fused magnesia, the lining beingattached by actually fusing the lining material to the wall of thecarbon tube. By virtue of the described construction I obtain not onlythe advantages arising from the magnesia being in a fused state, but Ialso prevent any warping or buckling of the lining material, since thelatter adheres strongly to the carbon surface and is not detached ordistorted .by the heat.

In specifying fused magnesia as the material of they lining I do notnecessarily mean magnesia which is actually melted at the time of use.

It is my purpose not only to line the carbon tube with fused magnesia,as above set forth, but also to coat the tube externally with the samematerial and vby substantially the same process.

In the present specification I not only show and describe a furnaceconstructed as above, but I also illustrate a method of attaching themagnesia in a fused state to the interior of the carbon tube.

It will be understood that the entire tube, consisting of the wall ofcarbon, with its lining and coating of fused magnesia, is to be Welljacketed by some good heat-resisting material, such as calcium oXid.

The first step in the manufacture of the described furnace is to preparethe carbon tube and coat it, preferably with fused magnesia, and thenjacket it with calcium oXid and provide circuit-terminals for the carbontube. The next and final step in the manufacture of the furnace is toattach the lining of fused magnesia. This I accomplish by arranging theotherwise-ready tube in a suitable cage, so that the tube shall behorizontal. Then by including the carbon tube as a resistance betweenthe terminals of the circuit (or any other suitable way) I vheat it hotenough to melt the magnesia, and I then rotate the tube, so as to causethe molten magnesia to floW over the inner surface of the carbon tube.In this way when suitable care is taken a dense even lining of fused.inagnesia can be spread upon the inner surface of the tube, thus supplying' a highly-refractory surface to the furnace-wall.

For many purposes, such as the Continuous operation required forproducing metallic chromium, it is of advantage to set the completedfurnace at an angle, say, of thirty degrees with the horizontal,.introducing the chrome oxid, with carbon, into the upper end of thefurnace and working it steadily through until metallic chromium runs outfrom the lower end into a suitable crucible. Such a process is describedby Moissan, and other continu ous processes, wherein a liquid(especially a viscous one) or a powder has to pass slowly through a tubeby reason of its own weight, are known to the art. All such processesare aided by turning or rotating the tube, and for this reason thepresent invention further contemplates the construction of a rotatoryelect-ric tube-furnace having' the capacity for rotation alreadydescribed and also having the capacity of causing' the tube to assumeany desired angle, as may be required by the different characteristicsof the materials treated in the furnace. Accordingly one feature of myinvention relates to the means whereby such rotation, whether horizontalor angular, may be obtained.

A tube-furnace such as that above described having a bore of two inchesand a length of one foot might well take over one thousand amperes atlive volts. I propose to transform this current into a current of, say,live arnperes and one thousand volts, and as a matter of convenience Ipropose to mount an adequate transformer or transformers, together withthe tube-furnace as a whole, in a barrel or on trunnions within asuitable cage and rotate the whole combination. This is another detailof my invention which will be fully described in the presentspecilication.

The foregoingligures are given merely as an example of magnitudes whichit is possible to use with a furnace such as I have invented.

My invention is illustrated in the accompanying drawings, in whichHFigure 1 is a longitudinal section through my electric furnace. Fig. 2is a transverse section therethrough; and Fig. 3 is an elevation and apart section of a completed furnace, showing the means for rotating' thesame and of adjusting its angular position.

Referring to Figs. 1 and 2, 1 is a tube of carbon, and 2 is the liningof fused magnesia. rI`he covering of fused magnesia is represented at 3,and end pieces of magnesia are shown at 4 4. r1`he whole is jacletedwith calcia or some other goed heat resisting material (shown at 5) andthis may in turn be surrounded by an outer casing-tube 6, of tile orPortland cement. The terminal connections are made tl'nough the mediumof split rings of metal, rings 8 8, of carbon, being inter posed betweenthe split metallic rings and the ends of the carbon tube. The splitrings 7 7 are provided with flanges 9 9 to assist in holding the endpieces f1- 1. A furnace thus constructed may be mounted, as shown inFig. 3, in a frame made up of beveled rings 1() 11 and crosspieces 1212, secured to the said beveled rings. The furnace is mounted in collars18 18, secured to rings 10 11, and its split-ring terminals 7 7 areconnected by leadwires let 1&1 to the secondaries 15 15 of transformers16 16, the primaries 17 17 of which are joined by wires 18 18 to collectnriugs 19 20. Through brushes 21. 22, which bear upon thecollector-rings 19 20, the primaries of the transformers are coi'mectedto the circuit 23 24 of the generator 25. At 26 I show acontrolling-switch for the generator-circuit and at 27 a conventionalregulator. rlhe furnace, (the outside casing of which appears at 6 inFig. 3,) the transformers 16 16, and the collector-rings 19 and 20,together with the insulated support 89 for the said rings, are allmounted on and held in position relative to one another by the framealready described. The transformers 16 16, as well as the collector-ringsupport 89, are fastened to the cross pieces or braces 12 12, as shown.The ring 10 :is plain, and the ring 11 is provided with gear-teeth. l hedescribed frame and its attached part are rotatory about the axis of thefurnace, and to this end it is carried in a cage carrying rollers 27,28, 29, and 30 and others not in the plane of the drawings, but similarand similarly mounted. The cage consists of rings 31 32, yolced bystraps 88 84. r1`he rollers 27 28 29 3() are mounted in the rings 31 and82. The rollers 29 and 80 are mitergeared and mesh with the gear of thering 11, the roller 30 being provided with a crank or turning it whenthe ring llland the parts connected therewith are to be rotated withinthe cage 31 82 38 81. The rollers 27 28 are smooth faced and againstthem bears the ring 10. The cage is supported from an eyebolt 36 andchain 87, there being' a second eyebolt 38 at the opposite end of thecage for tipping the cage at various angles other than that at which itwill hang from a single chain.

In operation current enters the transforrners from the line, and thesccondaries supply the requisite voltage and current through the tube 1,heating' it.

To form a lining for the tube, the latter is brought so that its axis ishorizontal, and a rod of inagnesia is inserted. The li'urnace beingheated enough to meltthe magnesia is ro tated by the handle 86 to causethemelted magnesia to flow over the inner-tube surface.

Vhen used for the purposes of a furnace, the latter is easily hung at anangle and the material to be heated passed .in from the upper end, therotation of the furnace causing IOS IIO

current-transformers for supplying current thereto, the furnace and thetransformer or transformers being attached to a common support, and thesaid support being adapted to rotate.

3. A rotary furnace having one or more current-transformers connectedthereto by suitable'terminals, the furnace and the transformers beingmounted upon a common support, the said support being provided withsuitable terminals connected withv the primary or primaries of thetransformer or transformers, and being adapted to rotate in combinationwith sliding or flexible connections coperating with the said terminals.

4c. A tubular electric furnace open at both ends and adapted to rotateduring its operation about the aXis of the tube or a parallel axis,means for maintaining said tube in any one of a selected number ofpositions with relation to the horizontal, and means for causing therotation of the tube in any selected position.

5. A tubular electric furnace adapted to rotate about the aXis of thetube, means for maintaining said tube in any one of a selected nurnberof positions with relation to the horizontal, means for rotating thefurnace in the selected position, the whole being supported in anadjustable cage, as set forth.

6. A tubular electric furnace mounted in a suitable frame, incombination with a cage outside the frame, and means for rotating theframe within the cage.

7. A tubular electric furnace mounted in a suitable frame, incombination with a cage outside the frame,means for rotating the framewithin the cage, and means'for adjusting the angle of the cage and theparts separated thereby.

8. Atubular electric furnace, a frame supporting the same, a cagesurrounding the frame, means for rotating the frame within the cage, andmeans for suspending the cage in a variety of positions with respect tothe horizontal.

Signed at New York, in the county of New York and State of New York,this 19th day of November, A. D. 1901.

' HENRY NOEL POTTER.

Witnesses:

GEORGE-H. STOGKBRIDGE, WM. H. CAPEL.

